2 PhD Positions in Laboratory Astrophysics in the OU Astrochemistry Group
Two positions are available starting Oct 2020 for PhD studentships in the group of Dr Helen Fraser.
2 PhD Studentships in Laboratory Astrophysics - Deadline Feb 21st 2020
If you would like to apply send a completed application form - home and EU students
or application form - overseas students
, an up to date CV, list of individual courses taken and grades obtained (or full course transcript), a personal statement of why you are interested in the particular project and how your skills match the research area, together with IETLS score (non UK nationals) to STEM-SPS-Phd@open.ac.uk by Feb 21st 2020. You are encouraged to contact the Dr Helen Fraser (firstname.lastname@example.org) prior to your application and to discuss the projects in more detail.
PhD 1:-Light-Field Motion Tracking in Laboratory Studies of Planet Formation
Overarching aim:- One of our key scientific drivers in the OU Astrochemistry group is to describe qualitatively and quantitatively the collisions that dominate the earliest stages of icy planetesimal-formation, to answer “how do planets form?”.
We aim to be the first in the world to develop and exploit an experimental payload to address this challenge, taking advantage of the high-quality, medium-duration microgravity environments in sub-orbital flight, to study sub-cm/s collisions between ensembles of ~nm-sized icy grains, forming µm-mm sized fluffy ice aggregates, that stick to form cm-sized icy pebbles. Without these specific microgravity conditions, our particles sediment (at the low velocities), the aggregates fall apart or compact (weight effects), and there is insufficient time to collide and aggregate all the particles.
The ability to attempt such collision experiments is only just emerging as sub-orbital flight providers commence operating, making this studentship timely for developing the underpinning technology ‘just in time’ to realize our scientific ambitions.
This scientific aim is reliant on the deployment of appropriate video camera technology capable of operating in low pressure (< 10-4 mBar), temperature (< 180 K) and microgravity conditions, to record, track, and subsequently compute, the 3D motion of every particle in the ensemble, accounting for appropriate illumination, adapting to opacity changes as the aggregation progresses, accounting for dynamic changes in particle orientation, occlusion, shadowing and range as a function of time, and ensuring rapid data storage (no lost frames at a high frame rate > 500 fps) over a sustained (> 240 s) period, in a field of view not smaller than ~ 100 cm3.
Consequently, the aim of this studentship is to develop this capability in a single, light-field camera with micro-lens array, and produce the associated software processing tools (with industrial partner DIAL). The methodology involves bread-boarding a prototype camera to a flight-ready model through two evolutions, at each step benchmarking, testing, and space-qualifying the camera technology by employing it in a range of scientifically-motivated laboratory and microgravity experiments, focused on icy-grain aggregation relevant to planet-formation processes, exploiting existing experimental set-ups at the academic partner (OU).
The major technological outcome of the studentship will be to demonstrate that 3D motion tracking of an ensemble of icy particles undergoing aggregating collisions in simulated planet-forming environments can be performed using a single light-field camera operating in video mode, concurrently addressing our scientific outcome; to enhance our empirical understanding of the processes that dominate the earliest stages of exoplanets, exomoon and exocomet formation.
Qualifications required: Masters in Physics or Engineering with significant experimental / instrumentational project work / research projects / internships in image technology / signal processing preferred. May suit Engineering students as much as those with a strong Physics background. With involve working with an industrial partner.
PhD 2:- Unveiling the Structure and Reactivity of Interstellar Ice with Neutron Scattering Studies
Overarching aim:- Another key scientific driver in the Astrochemistry group is to describe qualitatively and quantitatively the structure of the condensed materials found on tiny dust grains in star- and planet- forming regions. It is the “ice” structure that governs chemical reactivity, diffusion rates and consequently the degree to which molecular complexity can arise in star-formation environments, and form the bridge between diatomic species and those pre-biotic complex organic molecules that are required somewhere in the biosphere of a habitable planet such that life can emerge.
As the porous, amorphous ices are metastable and must be formed at low pressure and temperature, it is very difficult to produce and study the materials chemistry in a traditional sense. Therefore we have developed methods in the last few years to exploit novel neutron scattering techniques to understand the ice nano- micro- and macro- porosity. Our experiments have enabled us to see not only how water ice “grows” in space, but also how its structure is destroyed and modified by very low energy processes. This experimental work has been backed up by extensive molecular dynamics modelling.
Since our work to date has only focused on water-ice, the obvious next step in this research is to look at multi-molecular ice systems, from binary to mixed ices, more akin to those envisaged to form in interstellar star-forming regions. The second obvious step is to look at not the bulk ice growth, but those interactions right at the start – where water is aggregating on the nano-scale on the silicaceous and carbonaceous surfaces of the dust grains. Both of these next steps can be probed with neutron scattering techniques available at RAL-ISIS and ILL.
Therefore the aims of this PhD are two-fold:-
a. to study the dynamics of water adsorption and transport on model ISM surfaces of silicates and carbon, to look at the kinetic evolution of the water nano-clusters as a function of time and temperature
b. to study two model binary ice systems, CO-H2O and CH3OH-H2O using NIMROD and SANS2D instruments at ISIS. The experiments will involve dynamics studies of the ice growth and restructuring as a function of time and temperature, as well as the thermal evolution of the systems upon heating to destruction.
The student will be encouraged to link the work back to others in the research group working on surface dynamics, molecular dynamics, ice observations and place the resultant scientific data in both chemistry / physics and astronomy publications.
Qualifications required: Masters in Physics or Chemistry with significant experimental project work / research projects / internships condensed matter chemistry or physics. Previous beam-time or large scale facilities experience is welcome but not essential.